1. Field of the Invention
This invention relates to a damper arrangement for a check valve and, in particular, to a damper arrangement adapted to retard both opening and closing movements of a check valve.
2. Description of the Prior Art
Most check valves that are used in the petroleum production industry and which exhibit medium through large diameter sizes (on the order of twelve inches to fifty-two inches, respectively) are constructed in hinged clapper form. Clapper check valves of this type generally include a clapper, or valve member, which is keyed or otherwise securely mounted to a valve shaft. The valve shaft is mounted for rotary movement within an enlarged portion of the valve casing, the axis of rotation of the valve shaft being disposed transversely to the fluid flow path defined through the valve casing from an inlet port to an outlet port. The clapper and its shaft are thus free to pivot in an opening direction to permit fluid flow from the valve inlet port to the outlet port. However, if the fluid should begin to flow in an opposite direction (from the outlet port to the inlet port) the clapper is urged toward the seated position to prevent such backflow.
It is often desirable to retard or otherwise control the opening and closing movement of the valve clapper in order to prevent the application of large reaction forces to the valve casing and related components of a fluid system. U.S. Pat. No. 3,942,551 (Schuller, et al.) relates to a hydraulic damping mechanism for check valves used to prevent slamming of the clapper against a valve seat. U.S. Pat. No. 3,177,894 (Camp) and U.S. Pat. No. 3,789,872 (Elliott) likewise relate to mechanisms for damping the motion of check valve clappers. Each of these three above-cited patents (the first two of which are assigned to the assignee of the present invention) appear to disclose damping arrangements which are connected to the valve clapper through connecting rods which are hinged or otherwise pivotally mounted to the back surface of the clapper. U.S. Pat. No. 2,760,512 (Nechine) and U.S. Pat. No. 3,191,613 (Bagwell) each also appears to relate to a damping arrangement for a check valve.
U.S. Pat. No. 3,047,012 (Smith) and U.S. Pat. No. 3,106,220 (Hose) both appear to disclose a valve damper which includes a fluid casing within which a vaned rotary member is mounted for movement. The compression of damping fluid within the casing by the vane generates a damping force to retard the movement of the valve clapper.
U.S. Pat. No. 3,442,843 (Blackman, et al.) concerns a vaned damping arrangement which is provided with a pressure relief mechanism. The pressure relief mechanism takes the form of ball check valve disposed in each of the vanes of the rotary member and appears to permit the flow of damping fluid in only one direction through the vanes.